The study analyzed the data of 61 patients undergoing posterior lumbar interbody fusion (PLIF) from October 2021 to March 2023, where the observation group (n=29) used anticoagulants before surgery (LMWH n=11, indobufen n=18) and the control group (n=32) did not. All operations were successful with grade A healed incisions and no deep vein thrombosis of the lower extremities. There were no significant differences between groups in surgical time, intraoperative blood loss, postoperative drainage volume, number of blood transfusions, length of hospitalization, postoperative values of TT, FIB, APTT, PLT, HB, RBC, and HCT on the 1st, 4th, 7th, and last tested days (p > 0.05). There was a significant difference only in postoperative prothrombin time PT (p < 0.05), with no differences between the LMWH and indobufen subgroups. Multivariate regression analysis showed that the surgical segment was an independent factor of intraoperative blood loss (p < 0.05). Preoperative anticoagulants do not have a significant effect on postoperative TT, FIB, APTT and PLT (except PT) or on blood loss.